Thermostatic regulator



Oct. 23, 1934. E. FONSECA 1,978,362

THERMOSTAT I C REGULATOR Filed Feb. 5, 1934 ATTORN EYS Patented Oct. 23, 1934 PATENT OFFICE l 1,918,362 rnaauosra'rlc REGULATOR Edward L. Fonseca, Newark, N. J., assigner to The WilcolatorCompany, Newark. N. J., a corporation oi' Delaware application February s, maserati No. 'mam 1s claim. (ci. zas-1s) This invention relates to thermostatlc regulators and has reference particularly to thermostatic regulators for application to stoves. especially gas stoves, for controlling the temperature within the oven of the stove.

Thermostatic regulators for gas stoves in common commercial use for several years back have been to a very large extent of the type known as rod-and-tube instruments. This type of instrument includes an elongated rod and surrounding tube of metals having diilerent temperature coeillcients arranged to operate a valve controlling the gas supply, together with a setting handle for selecting the temperatures at which desired valve operations will occur. Usually such an instrument is inserted through an opening in the side-wall of the oven with the rod and tube projecting across the upper portion of the oven and the setting handle exposed upon the side of the oven above the burners of the stove.

Instruments of this type have been widely used and have proven very serviceable, but they have fallen far short of being as satisfactory as is desired. The general type of this instrument admits of insuilicient exibility of installation, and requires an undesirable amount of cutting of the oven wall, and the position of the operating handle above the open burners is undesirable, particularly so in modern types of gas stoves characterized generally as console ranges.

A very much superior type of thermostatic regulator for gas stoves is one wherein the heat-responsive element mounted within the oven is a bulb connected by a small flexible tube to an actuating device located outside the oven adjacent the gas controlling valve, the bulb, tube and actuating device containing a iluid which responds to temperature changes within the oven in such a Way as to actuate the gas-controlling valve appropriately. With such an instrument. the setting handle may be placed wherever is found to be most desirable, and particularly it need not be upon the side of the oven above the open burners where it is inconvenient and uncomfortably hot to manipulate it manually. Also the flexibility of the connecting tube permits of carrying this tube from the interior to the exterior of the oven in whatever way is most convenient, that is, with a minimum amount of cutting of the oven structure.

The advantages presented by this general type of instrument have long been recognized and much effort has been made to devise such an instrument in a form satisfactory for commercial use. However, all such eiort made heretofore has failed. Most investigators attacking this problem have proposed to employ a gas as the illling for the bulb, tube and actuating device referred to, but an instrument of this general type cannot be made in an acceptable form wherein the illling for the bulb, tube and valve-actuator is a gas.

The compressibility of gases precludes develop ment oi a pressure approximating that required` to operate the gas-controlling valve in response to such changes of temperature as occur in the oven of a gas stove unless the bulb mounted within the oven is of a size i'ar exceeding any permissible limits o1' size for a bulb for this use, and

even when employing such a bulb of a grossly excessive size it is doubtful whether satisfactory action of the gas-controlling valve could be secured in response to the eiect of temperature changes upon such a gas illling.

After extended study of the conditions presented in devising and employing such an instrument and experimentation over many years, I have been able to devise a thermostatic regulator of the general type referred to which is well adapted for use as a regulator for gas stoves, which operates with substantial accuracy, which may be installed quite readily by the stove manufacturer, and which may be manufactured at low cost. The distinguishing feature of my improved instrument is that the filling of the bulb, tube and valve-actuating device is a liquid, a nonmetallio, non-corrosive liquid, which will retain the requisite liquidity over a wide range of temtemperature variation extending up as high as the highest temperature reached in the oven in normal or even abnormal use thereof.

In the course of ordinary household cooking operations the temperature within the oven of a gas stove is apt to go up to 500 or 550 F. It is common to calibrate temperature regulators for gas stoves up to 550 F. Under somewhat unusual conditions the temperature may rise considerably above this and 650 F. may be accepted as representing the peak temperature reached in the oven. Therefore, the liquid filling for a temperature regulator of the type referred to must be one which will not vaporize at temperatures extending upto at least 650 F. Similarly, the

liquid employed must not be affected detrirnento the conclusion that an instrument of this type could not be made in a commercial form with a illling of a gas or of any substance which would gasify at the temperatures commonly reached. On the other hand, a liquid would serve the purpose admirably because of being relatively noncompressible with the result that the expansion in a small body of liquid in a bulb located in the oven would serve adequately to operate the actuating device of the gas-controllingl valve. But the requirements of a liquid which would serve the purpose adequately are rather rigid and great difficulty was experienced in determining upon a suitable liquid. The use of mercury in thermometers and other temperature-responsive devices suggested its use, particularly as it has been suggested that mercury be employed in a thermostatic controlling device for a household radiator. But use of mercury in an instrument of the type referred to is impracticable. A small capillary tube of the requisite flexibility for connecting the bulb in the oven with the valve-actuator outside the oven is best made of copper and copper would be attacked by mercury because of the continuous progressive amalgamation that takes place at the high temperatures to which a portion of the tube is subjected as well as the resulting variation in the thermostatic characteristics of the mercury because of this continuous solution of the copper thereby, so that the device would soon become inaccurate. Also, the valve-actuator is best made in the form of a flexible bellows of thin copper, and this too would be attacked by mercury. Thus it is evident that a satisfactory liquid filling must be one that does not amalgamate with the metallic part of the device, and one that is otherwise non-corrosive.

A liquid which I have demonstrated serves the purpose admirably is chlorinated diphenyl, preferably diphenyl containing chlorine to the extent of approximately 48% by weight. This substance retains its liquidity at elevated temperatures running up as high as 650 F. and in that respect is entirely adequate for use as an actuating uid in a temperature regulator. Also, it retains its liquidity all the Way down from that point to room temperature; below ordinary room temperature it thickens somewhat, its pour point being about 16 F.. but it does not stiifen at temperatures well belowthis. Also, there is no substantial change of volume with changes of temperature in the lower ranges such as would preclude use of this liquid. In the higher ranges, that is, temperatures prevailing in the oven during its operation, this liquid responds to changes of temperature by changes of volume which are entirely adequate and in fact are admirably proportioned to use in the manner indicated. The bulb employed may be of small proportions so that it does not take up an undue amount of space within the oven, and even so the expansion of the liquid therein will be ample for use in effecting operation of the gas-controlling valve.

My invention, therefore, involves the provision of a thermostatic regulator for use upon a gas stove to control the suppy of gas to the oven burners wherein the valve for regulating the flow of the gas is controlled by an actuator of the bellows type connected by a capillary tube to a bulb located within the oven, the bulb, tube and bellows being completely filled with a non-metallic, non-corrosive liquid which is distinctive in the respect that it will retain its liquidity over the full range of temperature to which the bulb in the oven will be subjected during all ordinary and extraordinary cooking operations and intervals between cooking operations. More specifically the invention involves the provision oi' such a thermostatic regulator wherein the liquid employed as the illling for the bulb, tube and bellows will retain its liquidity over a range of temperature changes from approximately zero up to approximately 650 F., an excellent example of such a liquid as is suitable being chlorinated diphenyl.

In adapting the invention for practical use in the commercial supply of thermostatic regulators for gas stoves, I prefer to embody the invention in a form of regulator which includes a thermostatic compensating means located outside the oven and arranged to offset the effect vof local temperature existing outside the oven, which, if not sooilset, would have a bad effect upon the accuracy ofthe instrument as a whole. This compensating means may conveniently consist of a piece of thermostatic metal interposed in the connection between the bellows and the valve, this strip being arranged to respond to temperature changes existing in its immediate neighborhood in such a way as to compensate for their eilect upon the liquid in the bellows. A thermostatic regulator of this type is disclosed in my co-pending application Serial No. 575,525, illed November 17, 1931, of which the present application is a continuation in part. It is to be understood, however, that the present invention need not be associated with the self-compensating feature of the parent application, but may be employed with equal facility without it, depending uponv the location of the regulator on the range and other manufacturing or installation requirements.

For a more complete understanding of the invention reference may be had to the accompanying drawing, in which Fig. 1 illustrates one way of mounting the new heat regulator of this invention on a gas' range of the console type;

Fig. 2 is a longitudinal section through the regulator; and

Fig. 3 is a longitudinal section through a modied form of the regulator.

As is illustrated in Fig. 1 of the drawing, the inner side wall 10 of the oven 11 of a console range is only about six inches in height, so that it is impracticable to mount the usual rod-and-tube thermostat in its usual place on the wall 10 because not only is it so close to the open exterior burners l2 as to be liable to injury by pots and pans moved around on the burners l2, but is also subject to the heat emitted by the exterior burners l2. This extraneous heat makes the adjusting handle uncomfortably hot and aects the operation oi the thermostat so that it is not accurate in operation but fluctuates with the turning on and ofi" of the exterior burners.

With the present invention, the regulator need not be mounted in the usual place on the inner wall 10 of the oven 11, but may be mounted anywhere, regardless of the heat emitted by the exterior burners 12. For example, as is illustrated in Fig. 1, the regulator 13 may be mounted beneath the exterior burners 12 adjacent the manifold 14 and behind the front panel l5, so that all pipe connections are concealed and the pleasing and less utilitarian appearance of the modern range is preserved. This optional positioning of the new regulator is rendered possible both by the flexible connection of the thermostat bulb 16, which is afforded by the flexible metal capillary tube 17, and also because the regulator is selfcompensating to eliminate the disturbing effects of the heat emitted by the exterior burners 12 no matter how close to these burners the regulator is located.

In the arrangement illustrated in Fig. 1, the regulator 13 may be conveniently supported by a pipe 18 connecting it with the manifold 14 and including the gas cock 19. The outlet of the regulator 13 communicates with the oven burner 20 by means of the pipe 21, while the pilot burner 22 for the oven burner 20 is connected with the regulator 13 by a small tube 23. Similar connections may be made, depending upon the position selected for the regulator 13. Capillary tube 17 passes through4 a small hole drilled in the wall of the oven either through or below the insulation thereof, thereby saving insulation, reducing the labor and avoiding cutting large holes in the walls of the oven, Further, this simple installation of the new regulator enables the manufacturer of the range to install it without materially increasing the cost of the finished range above the actual manufacturing costs of the range and regulator.

Referring to Fig. 2 of the drawing, the reguvlator 13 comprises a valve body formed with two parts, 24 and 25, which are suitably secured together by screws 26 and sealed by a gasket 27. 'Ihe valve body part 24 is separated into two chambers 28 and 29 by a valve 30 resting on valve seat 31. The gas supply pipe 18 communicates with chamber 28 and the gas outlet pipe 2l with chamber 29. J ournaled through the wall of the valve body part 24 is a shaft 32 passing through an opening in the front panel 15 of the range and having on its outer end a knob and dial combination 33, whereby the shaft 32 may be rotated. The inner end of the shaft 32 is provided with a slotted yoke 34 which is provided with a conical shoulder 35 cooperating with a corresponding conical seat in valve body part 24 to seal the shaft gas-tightly in the valve body part 24, spring 36 being interposed between a disc 37 on the shaft 32 and the valve body part 24 to hold the conical shoulder 35 in its seat.

The valve 30 is slidably mounted on the outer surface of a nut 38 threaded on a double-pitch screw 39 and having keys 40 which fit into the slots of the yoke 34, so that as knob 33 is rotated the nut 38 is advanced axially along screw 39 until the keys 40 engage the stem of valve 30 to change its position with respect to valve seat 31.

The inner end of screw 39 pivotally carries a disc 41 between which and the valve 30 is interposed a spring 42 which urges the valve 30 against its seat 31. Secured to the disc 41 by one end is a compensating thermostat 43 of U-shape, the other end of which is mounted on a push rod 44 secured to the bottom of a cup 45 and slidable through a guide plate 46 clamped between the valve body parts 24 and 25. A spring 47 interposed between the bottomof cup 45 and plate 46 urges cup 45 to the left, as seen in Fig. 2. The compensating thermostat 43 is preferably a bimetallic strip bent in loop form and arranged to contract in response to temperature increases and expand in response to temperature decreases, the pivotal connection between disc 41 and screw 39 permitting the strip 43 to flex in this fashion.

The cup 45 is connected to a disc 48 sealing one end of a flexible metal bellows 49, the other end of which is sealed by a plug 50 threaded through valve body part 25 and held in place by a nut 51. Communicating with the interior of bellows 49 through a hole 52 drilled in plug 50 is the flexible capillary tube 17 of metal, preferably copper. This tube has substantial length and is sufnciently ilexible to be bendable ai'ound corners in any direction to conform to the interior shape of the oven 11 and the like, as is illustrated in Fig. 1. Communicating with the capillary tube 17 is the bulb 16 consisting of an elongated metal cylinder of copper or the like and arranged to be mounted within the oven 11 preferably across the top of it just inside the door, as is illustrated in Fig. 1.

Plug 50 is provided with a short capillary i111- ing tube 55 which, after sealing off, is wrapped around capillary tube 1'7 to protect it against rupture while bending. 'I'he interior of bellows 49, capillary tube 17, and bulb 16 are completely filled tothe exclusion of all vapors, air, and other gases, with a thermostatic liquid, preferably by means of lling tube 55 which is then sealed of! at 56. As was previously mentioned, I have found chlorinated diphenyl, containing chlorine to the extent of about 48% by weight, to be an admirable thermostatic liquid for uniform operation, sensitivity and stability throughout the wide range of temperatures to which it is subjected in the oven of a gas range, this temperature range extending from a low room temperature to as high as 650 F., although in ordinary operation of the range oven the temperature does not extend materially above 550? F., which is the temperature to which thermostatic regulators are commonly calibrated. Also, this liquid is not corrosive, so that it does not. deteriorate the bulb, tube and bellows combination, nor does it amalgamate as does mercury with the non-ferrous metals such as copper, of which the regulator, tube and bellows combination is preferably made for operating, assembling, and manufacturing reasons.

I have also found that the ratio of the liquid volume in the bulb 16 to the liquid volume in the bellows 49 should not be more than two or three to one for the reason that a larger ratio would result in a dangerously large extension of the bellows at the high temperatures to which the liquid is subjected.

A by-pass 57 controlled by needle valve 53 connects chambers 28 and 29 so that a small but constant supply of gas flows around the valve when cock 19 is open so as to prevent extinguishing of the oven burner 20 when the valve 30 is nearly closed at low temperature operation of the oven. By-pass 57 communicates with the tube 23 supplying pilot burner 22, which accordingly remains continually lighted.

In operation, rising temperatures within the oven cause the thermostatic liquid, which lls the bulb 16 and capillary tube 17 and the bellows 49 to expand in proportion to the temperature increase and extend the bellows 49 so that valve 30 is moved toward closed position, reducing the supply of gas passing the valve to the oven burner 20, so that the temperature of the oven is accordingly reduced. The degree of travel of the valve 30 is regulated by means of the knob 33, which positions the valve with respect to its seat in accordance with the axial position of nut 38 upon which the valve 30 is slidably mounted.

In response to the heat emitted by the exterior 1 that the liquid in bellows 49 expands in response thereto, so that the disturbance which would ordinarily be created by the extraneous temperature is nullied and the position of the valve 30 is not altered, but is positioned by the thermostatic system only in accordance with the temperature within the oven 11. The reverse takes place when one or more of the outside burners 12 is turned off, reducing the extraneous temperature to which the thermostatic system is subjected. Accordingly, as the liquid in bellows 49 tends to contract because of the reduction of the temperature to which it is exposed, thermostatic strip 43 expands to compensate for this contraction of the thermostatic liquid, whereby the position of the valve 30 is unaffected and the temperature of the oven is maintained constant.

A modied form of the new thermostatic regulator is designated 13' in Fig. 3 and comprises a valve body 60, having a gas inlet chamber 61 and a gas outlet chamber 62, the communication between which is controlled by valve 63 urged on its seat by spring 64. A by-pass 65 controlled by needle valve 66 permits a small amount of gas to ow when cock 19 is open to prevent extinguishing of the oven burner 20 when the valve 63 is nearly closed during low temperature operation of the oven 11.

A shaft 67 journaled through valve body 60 and projecting through an opening in panel 15 is provided with a knob 68 for adjusting the thermostat. Axially splined on the'inner end of shaft 67 is a nut 69 threaded on a stem 70, the free end of which is secured to cap 71 of a flexible metal bellows 72. As knob 68 is rotated nut 69 moves along stem 70. Thev bellows 72 is urged toward distended position by a spring 73 seated on cap 71 and engaging a ring 74 at its other end. Enclosing the bellows 72 and sealed on the valve body 60 is a cup 75, the interior of which forms, with the exterior of the bellows 72, a closed annular chamber 72', the volume of which is varied by the extension and contraction of the bellows 72. Sealed through the wall of cup 75 is a nipple 76, through which communicates with the bellows chamber 72' a ilexible capillary tube 17', communicating` at its other end with the bulb 16'. The bulb 16', the capillary tube 17', and the chamber 72 are completely lled with the aforementioned thermostatic liquid to the exclusion of all vapors, gases and other foreign material.

Connecting the valve 63 with the thermostatic system is a compensating thermostat in the form of a lever 77 comprising a bi-metallic strip arranged to respond to extraneous temperatures to compensate for the eiects ,of these temperatures on the thermostatic system, this compensating thermostat 77 corresponding to bi-metallic strip 43 in the arrangement-of Fig. 2. In the modification of Fig. 3, this strip also acts as a lever to communicate the movement of the thermostatic system and the adjustment provided by knob 68 to the valve 63. To this end the compensating thermostat 77 is connectedat one end to valve 63, fulcrumed at 78 intermediate its ends, and connected at its other end to nut 69. As this nut is adjusted by knob 68 its movement is communicated to Valve 63 by compensating thermostat 77, and as the bellows 72 expands and contracts its movement is communicated to valve 63 by stem 70, nut 69, and compensating ther-- mostat 77. The form of regulator illustrated in Fig. 3 is disclosed in my co-pending application Serial No. 650,255, led January 5, 1933, and its novas operation will be readily understood as being the same as that of the form illustrated in Fig. 2.

While certain preferred embodiments of the invention have been illustrated and described herein, it is to be understoodthat the invention is not limited thereby, but is susceptible of varous changes in form and detail within its scope.

I claim:

1. In a thermostatic regulator for the heater of an oven, the combination of temperature regulating means therefor, a bulb in the oven, an expansible and contractible chamber connected to said means, a tube connecting the bulb and chamber, and a non-metallic thermo-responsive liquid completely filling the bulb, tube and chamber and retaining its liquidlty at the normal working temperatures of the oven up to 650 F., the expansion and contraction of the liquid in the bulb in response to temperature changes in the oven being communicated to the chamber for actuating the temperature regulating means.

2. In a thermostatic regulator adapted to be mounted 'upon a gas stove and to control the supply of gas to the burner of the oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a valve in the casing for controlling the flow from the inlet to the outlet, an operating member for the valve, a manual adjustment for regulating as desired the connection from said member to the valve, an expansible metallic chamber connected to said member for operating it, a 4metallic iiexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, and a nonmetallic liquid completely filling the bulb, tube and chamber, which liquid has the physicalproperty of diphenyl containing approximately 48% chlorine by weight of retaining its liquidity throughout normal working temperatures in the oven up to 650 F.

3. In a thermostatic regulator adapted to be mounted upon a gas stove and to control the supply of gas to the burner of the oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a valve in the casing for controlling the flow from the inlet to the outlet, an operating member for the valve, a manual adjustment for regulating as desired the connection from said member to the valve, an expansible metallic chamber connected to said member for operating it, a metallic exible tube connected to the chamber, avbulb connected to the tube and adapted to be mounted in the oven, and a nonmetallic liquid completely filling the bulb, tube and chamber, which liquid retains its liquidity throughout temperature variations in the oven from room temperatures up to 650 F.

4. In a thermostatic regulator for an oven, the combination of a fuel valve, a bulb in the oven, an expansible and contractable chamber connected tothe valve for actuating the valve, a tube connecting the bulb and chamber, and chlorinated diphenyl completely filling the bulb, tube. and chamber as a thermo-responsive liquid, the expansion and contraction of which in response to temperature changes in the oven are communicated to the chamber for actuating the valve.

5. In a thermostatic regulator for an oven having a heater, the combination of a movable member controlling the heater, a bulb in the oven, an expansible and contractable chamber connected to the member for actuating it, a tube connecting the bulb and chamber, and diphenyl containing approximately 48% chlorine by Weight completely filling the bulb, tube and chamber as a thermo- Cir responsive liquid, the expansion and contraction of which in response to temperature changes in the oven'are communicated to the chamber for actuating the said member.

6. In a thermostatic regulator adapted to be mounted upon a gas stove and to control the supply of gas to the burner of the oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a valve in the casing for controlling the flow from the inlet to the outlet. an operating member for the valve, a manual adjustment for` regulating as desired the connection from said member to the valve, an expansible metallic chamber connected to said member for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, and chlorinated diphenyl completely filling the bulb, tube and chamber as a thermo-responsive liquid, the expansion and contraction of which in response to temperature changes in the oven are communicated to the chamber for actuating' the valve.

'7. In a thermostatic regulator adapted to be mounted upon a gas stove and to control the supply of gas to the burner of the oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a valve in the casing for controlling the flow `from the inlet to the outlet, an operating member for the valve, a manual adjustment for regulating as desired the connection from said member to the valve, an expansible metallic chamber connected to said member for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube andl adapted to be mounted in the oven, and diphenyl containing approximately 48% chlorine by weight completely filling the bulb, tube and chamber as a thermo-responsive liquid,I the expansion and contraction of which in response to 4temperature changes in the oven are communicated to the chamber for actuating the valve.

8. In a thermostatic regulator adapted to be mounted upon a gas stove and to control the supply of gas to the burner of the oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a valve in the casing for controlling the flow from the inlet to the outlet, an operating member for the valve, a manual adjustment for regulating as desired the connection from said member to the valve, an expansible metallic chamber connectedto said member for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, and chlorinated diphenyl completely filling the bulb, tube and chamber as a thermo-responsive liquid retaining its liquidity throughout temperature variations from room temperatures up to 650 F.

9. In a thermostatic regulator adapted to' be mounted upon a gas stove and to control the supply of gas to the burner of the oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a Valve in the casing for controlling the flow from the inlet to the outlet, an operating member `for the valve, a manual adjustment for regulating as desired the connection from said member to the valve, an expansible metallicchamber connected to said member for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, and diphenyl and at least one substance combined therewith toform a liquid having a vaporizing point above 650 F., which completely fills the bulb, tube and chamber as a. thermo-responsive material, the expansion and contraction of which in response to temperature changes in the oven are communicated to the chamber for actuating the valve.

10. In a thermostatic regulator for an oven, the combination of a casing, a gas inlet and a gas outlet connected to the casing, a valve in the casing for controlling the flow from theA inlet to the outlet, an expansible chamber connected to the valve for actuating the valve, a bulb in the oven, a tube connecting the bulb and chamber, a non-metallic, thermo-responsive liquid completely filling the bulb, tube and chamber, which liquid retains its liquidity throughout temperature variations from room temperatures up to 650 F., and means responsive to temperatures outside of the oven for compensating for the effect of such outside temperatures on the liquid.

11. A thermostatic regulator for an oven having a heater comprising the combination of a casing, a movable means located within the casing for controlling the heater to regulate the temperature within the oven, an expansible chamber connected to said means for actuating it, a bulb in the oven, a tube connecting the bulb and chamber, a non-metallic, thermo-responsive liquid completely filling the bulb, tube and. chamber, which liquid retains its liquidity throughout ternperature variations from room temperatures up to 650 F., and means responsive to changes of 105 temperature outside the oven acting upon said movable means to compensate for the effect ot such outside temperatures upon the said liquid.

12. A thermostatic regulator for an oven having a heater comprising the combination of a casing, a movable means located within the casing fori controlling the heater to regulate the temperature Within the oven, an expansible metallic chamber connected to said movable means for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, a non-metallic liquid completely filling the bulb. tube and chamber, which liquid has the physical property of diphenyl containing approximately 48% chlorine by weight of retaining its liquidity throughout temperature variations in the oven from room temperature up to 650 F., and a manual adjustment for aiecting the connection from said chamber to the said movable means.

13. A thermostatic regulator for an oven having a heater comprising the combination of a casing, a movable means located within the casing for controlling the heater to regulate the temperature within the oven, an expansible metallic chamber connected to said movable means for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, a non-metallic liquid completely filling the bulb, tube and chamber, which liquid has the physical property of diphenyl containing approximately 48% chlorine by weight of retaining its liquidity throughout temperature variations in the oven from room temperature up to 650 F., a manual 140 adjustment for affecting the connection from said chamber to the said movable means, and thermoresponsive means located outside the oven and responsive to changes of temperature outside the oven for compensating for the effect of such out- 145 side temperatures upon the said liquid.

14. A thermostatic regulator for a gas stove for controlling the supply of gas to the burner of the oven, comprising the combination of a casing, a gas inlet and a gas outlet connected with 150 the casing, a valve in the casing for controlling the ow from the inlet to the outlet, an operating member i'or the valve, a manual adjustment for regulating as desired the connection from said member to the valve, an expansible metallic chamber connected to the said member for operating it, a metallic ilexible tube connected with the chamber, a bulb connected with the tube and adapted to be mounted in the oven, a non-metallic liquid completely illling the bulb, tube and chamber, which liquid has the physical property of diphenyl containing approximately 48% chlorine by weight of retaining its liquidity throughout temperature variations in the oven from room temperatures up to 650 F., and a thermo-responsive means located outside the oven and responsive to changes of temperature outside the oven and acting upon said valve to compensate for the eiect of such outside temperatures upon the said liquid.

15. A thermostatic regulator for an oven having a heater comprising the combination of a casing, a movable means located within the caslng for controlling the heater to regulate the temperature within the oven, abulb in the oven, an expansible and contractable chamber connected to said movable means for actuating it, a tube connecting the bulb and. chamber, and chlorinated diphenyl completely filling the bulb, tube and chamber as a thermo-responsive liquid, the expansion and contraction oi which in response to temperature changes in the oven are communicated to the chamber for actuating the said movable means.

16. A thermostatic regulator for an oven having a heater comprising the combination ci a casing, a movable means located within the casing. for controlling the heater to regulate the temperature within the oven, an expansible metallic chamber connected to said movable means for operating it, a metallic flexible tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven,

a nlling of chlorinated diphenyl in the bulb, tube and chamber as a thermo-responsive liquid retaining its liquidity throughout temperature variations trom room temperatures up to 650 F., and a manual adjustment for regulating as deslredthe connection from said chamber to said movable means.

17. In a thermostatic regulator for an oven having a heater, the combination of a movable member for controlling the heater, an expansible and contractable chamber connected to said member for operating it, af'tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, and diphenyl and at least one substance combined therewith to i'orm a liquid having a vaporizing point above 650 F. which completely illls the bulb, tube and chamber as a thermo-responsive material, the expansion and contraction of which in response to temperature changes in the oven are communicated to the chamber for actuating the said member.

18. The combination with an oven having a heater, of a thermostatic regulator having a movable member for controlling the heater, an expansible and contractable chamber connected to the member for operating it, a tube connected to the chamber, a bulb connected to the tube and adapted to be mounted in the oven, a lling of diphenyl and at least one substance combined therewith to form a thermo-responsive liquid which retains its liquidity over ranges of temperature extending from a low room temperature to above 650 F., the said liquid completely filling the bulb, tube and chamber and expanding and contracting in response to temperature changes in the oven to cause said chamber to actuate the said member, and a thermoresponsive means located outside the oven and responsive to changes of temperature outside the oven for compensating for the eiect of such outside temperatures upon the said liquid.

EDWARD L. FONSECA. 

